Collimators are optical devices that are used to focus and direct light that is emitted from a light source. One such light source might include a light-emitting diode, otherwise called an LED. The collimator is placed on top of the light source such that light is received by the collimator. Collimators typically have a main body that is shaped like a cone or a parabola and a centerline that extends through the collimator body. A collimator may also include an internal lens that receives the light from the light source. The collimator has a characteristic called total internal reflectance (or “TIR”), which means that the collimator refracts the rays of light and emits them in a direction generally parallel to the optical axis, which is generally coincident with the centerline of the collimator. Thus, collimators may be used to focus and direct light in the direction of the optical axis.
A light source is typically mounted on a board such that both the board and the light source lie in a horizontal plane. Because the light source is mounted horizontally, the light is emitted in a vertical direction. However, it may be desirable for the light to be emitted in directions that are not vertical. It may not be possible to simply angle either the mounting board or the light source in the desired angle due to design constraints. Thus, other methods must be used to control the angle of the emitted light.
For example, a collimator may be used to angle the direction that the light is emitted. One known solution is to tilt the collimator relative to the light source. Thus, the light source and mounting board remain horizontal, and the collimator is tilted relative to the light source. The light will be emitted out of the collimator in a direction approximately parallel to the optical axis due to the TIR of the collimator. Thus, because the collimator itself is tilted, the optical axis and the direction of emitted light are also tilted. One problem with such a method is that an open space or gap is typically created between the light source and the base of the collimator by virtue of such tilting. Thus, not all the light enters the collimator—some of the light escapes through the open space. Tilting the collimator may therefore result in a loss of energy, which might cause problems associated with heat and optical efficiency management.
Another known method is to use a prismatic optic in conjunction with the collimator. The prismatic optic has prisms that are tilted and angled in particular directions. In order to angle the light in a desired direction, a prismatic optic is selected that corresponds to that direction. The prismatic optic is placed on top of the collimator. Light is emitted from the collimator in a direction approximately parallel to the optical axis, enters the prismatic optic, and is emitted from the prismatic optic as refracted by the prisms in the prismatic optic. But one problem is that the extra optical surface will result in an energy loss of 8-10%, commonly referred to as Fresnel losses. Yet another problem is that each prismatic optic has prisms that are angled in only one direction. Thus, if light must be directed in a new angle, a new prismatic optic must be selected for that new angle. Such methods increase cost and manufacturing time.
Thus, there is a need for a collimator that can direct light in particular directions while minimizing energy loss.
There is also a need for a collimator that can direct light without the need for additional parts or optics, such as a prismatic optic.
Finally, there is a need for inexpensive and time-efficient methods of manufacturing collimators.